Checking a provider: what matters

Updated: August 2026 · 15 min read · eBilanz Fabrik — information, not tax advice

For software that prepares a tax return or an E-Bilanz — the Bilanz and Erfolgsrechnung, balance sheet and income statement, in structured electronic form — there is no official approval in Canton Zürich: the cantonal tax office's Merkblatt (guidance leaflet) of 15 November 2005, ZStB 109c.3, states that commercially available products from private providers are «durch das kantonale Steueramt nicht geprüft (homologiert)» — neither checked nor homologated by the cantonal tax office. The check is therefore yours. This page is the checklist we would run it with, and our own answers stand in the same table so you can turn it on us.

This page is information. It is not Steuerberatung (tax advice) and not legal advice. Whether any of these questions matters for your company is for you or your Treuhänder — the Swiss fiduciary who keeps the books and deals with the tax office — to judge, not for us.

Every source here is German-language. Quotations are rendered in English; where the exact wording carries the weight the German original stands in «guillemets», and the German is what governs.

1 · What the canton binds itself to — the yardstick you can pass on

The ordinance on electronic filing of the tax return (Verordnung über die elektronische Einreichung der Steuererklärung, LS 631.121, in the version of the decree of 13 May 2025, in force since 1 July 2025) binds the cantonal tax office in § 3 para. 1 to take the necessary measures: so that data filed electronically «nicht verändert oder gelöscht werden können» — cannot be altered or deleted; so that the Steuergeheimnis under § 120 StG — the statutory tax secrecy that binds the authorities — is guaranteed and no unauthorised persons have access to the data; and so that it can be traced at any time which persons accessed which data.

The densest sentence is in § 3 para. 2: «Die Steuerämter dürfen die Steuererklärungsdaten erst einsehen und bearbeiten, wenn die steuerpflichtige Person sie gemäss § 8 eingereicht hat. Die erfassten Daten werden verschlüsselt übermittelt und auf dem Server abgelegt.» — the tax offices may not inspect or process the data until the taxpayer has filed it, and the data captured is transmitted and stored on the server in encrypted form. Both halves translate word for word into a question you can put to a provider. § 2 defuses one naive demand at the same time: the canton stores the data on servers «von ihm oder in seinem Auftrag betriebenen», operated by it or on its behalf. So the useful question is not whether sub-processors exist, but: which ones, where, and under what contract?

Traceability is not the same as a visible change log

The requirement in § 3 para. 1 lit. d binds the tax office, and concerns access to data already filed. Asked whether it is apparent who makes a change, the cantonal tax office answers in «Fragen und Antworten» of 8 September 2025 that the information "is partly present in the database but is not visible to users in the application". The same document states: "ZHcorporateTax offers no role model with differentiated permissions. A tax return can be shared, whereby all users have the same rights." Sharing therefore also means: they can file it.

2 · Where your data is processed — and which law applies there

A domain ending tells you nothing about this. Our own privacy notice (as at 4 August 2026) therefore says expressly that these pages are served "from a server location in Nuremberg, Germany", while the domain and the name servers sit with a registrar in Rapperswil-Jona which "does not deliver these pages". Under the same notice, "the General Data Protection Regulation (GDPR) applies in the first place" to us, because it attaches "to the place of the controller's establishment — not to the country code of the domain and not to the customer's seat" (Art. 3 (1) GDPR). Alongside it, the revised Swiss Data Protection Act applies under the effects principle (Art. 3 DSG); a complaint can be made in either direction — under Art. 77 GDPR, and to the EDÖB in Bern under Art. 49 DSG.

The error a blanket "GDPR-compliant" conceals

Both regimes protect the data of natural persons only. The revDSG expressly removed the protection of legal persons with the revision of 1 September 2023; the GDPR never covered it (Art. 4 (1) GDPR). The figures in the Bilanz and Erfolgsrechnung of an AG or a GmbH — a Swiss stock corporation or limited company — are therefore in principle not personal data — it is otherwise where information can be related to a specific natural person, with an Einzelunternehmen (sole proprietorship) for example. What protects your figures is mostly the contract: do not only ask which statute is cited, ask what has been promised in writing about the figures themselves.

3 · Who transmits — and whose credentials are in play

The standard declares itself out of scope here. eCH-0276 «E-Bilanz und E-Tax JP» records in section 1.3 (V1.0.0 of 19 November 2024; word for word the same in the draft V2.0.0 of 3 July 2026): "The standard does not deal in detail with the subject of the transmission of the data […]" and "The standard does not deal with the visualisation of the XML data, their transport and the encryption necessary for it." Section 4 adds that eCH standards «haben nur den Status von Empfehlungen» — they have the status of recommendations only. A data format can therefore promise neither a transmission route nor the security of one.

What the route looks like is set out in swissdec's technical specification «eBILANZ — Anforderungen Transmitter» (edition of 6 March 2026). It knows two business processes — the E-Bilanz in XBRL from the ERP system to a canton's own declaration solution, and eCH-0276 from a declaration solution to the main and secondary tax domiciles — and states: "For contractual and statutory reasons on swissdec's side, currently only cantons' own declaration solutions can receive the E-Bilanz electronically via the Distributor." Every transmission "must be signed and encrypted", with a company certificate. According to swissdec the programme is in its pilot phase, with productive operation from 2027 — that is swissdec's statement about its own programme, not a commitment by any canton.

The cantonal tax office of Zürich writes on 8 September 2025: "At present no connection to Dr. Tax is available. […] Whether third-party applications will be connected via the existing ZHservices interface (as for natural persons) or not is not yet clear." Dr. Tax itself writes in its own helpdesk, in the entry for Canton Zürich under the heading «Steuererklärung JP» — the return for legal entities: «Es ist derzeit keine elektronische Einreichung möglich», electronic filing is not currently possible (article 115000806069, last updated 3 July 2026). If a provider tells you "we transmit for you", the follow-up question is: by which route, and with whose certificate?

Two sets of credentials, two entirely different effects

AGOV describes itself as «das neue Behörden-Login der Schweiz», the new authorities' login of Switzerland, and works without a user name or password; what you register is your own e-mail address plus an access app or a security key (agov.ch, retrieved 4 August 2026). It identifies a natural person and is in practice not something you can hand over.

The Registernummer for portal access and the Zugangscode are the transferable pair, and handing them over is the grant of authority: «Die steuerpflichtige Person kann Drittpersonen durch Übergabe der Zugangsdaten bevollmächtigen, ihre Steuererklärungsdaten über die Applikation zu erfassen und die Steuererklärung elektronisch einzureichen» — the taxpayer may authorise a third party, by handing over the credentials, to capture the tax-return data in the application and file it electronically (LS 631.121 § 11 para. 1). It is revoked by requesting a new Zugangscode, sent "by post to the address listed in the tax register" (para. 2). Canton Obwalden shows the same construction: a personal login with «Zwei-Faktor-Authentifizierung per SMS», two-factor authentication by SMS, plus "the access credentials from the tax-return notification, which we send you by post at the end of February each year" (Merkblatt on the login, as at 18 February 2026).

4 · What is fixed once you have filed — and what you get back as evidence

Up to the moment of filing, the taxpayer may change or delete the captured data "at any time" (LS 631.121 § 7 para. 3); afterwards no longer — «Nach dem Einreichen lässt sich die Steuererklärung nicht mehr löschen. Sie bleibt in Ihrem Konto aufgeführt», the return cannot be deleted after filing and stays listed in your account (ZHcorporateTax support, article «Steuererklärung löschen», created 18 July 2025, edited 17 September 2025). A correction is not an edit but a fresh filing (§ 9).

As evidence, according to «Fragen und Antworten» of 8 September 2025, the filed return, the Übermittlungsquittung (transmission receipt) and the provisional tax computation are each available individually as a PDF, and the Belege (supporting documents) as a ZIP; Verfügungen (assessment rulings) and invoices still arrive by post as before. That a document handed back can also be signed is documented: the E-Bilanz guide published by Canton Obwalden (as at 16 February 2023) says «Das PDF ist mit einem Swisscom TSA 3 Zertifikat signiert» — the PDF is signed with a Swisscom TSA 3 certificate. So ask concretely: what do I get back, is it signed or time-stamped — and what does it actually attest to? Our own answer is a narrow one: we deliver a file; it says nothing about your filing, because we never touch it.

5 · Retention: the question you can test in thirty seconds

Ask for the deletion period. Then ask what actually happens on the day it expires. A published period with no mechanism behind it is worse than none — a mistake we made ourselves and corrected on 2 August 2026: our privacy notice named a 90-day deletion that nobody technically performed. Today it reads "No automatic deletion period is currently active, and we deliberately name no period here that we cannot technically keep" (as at 4 August 2026).

The other half is statutory retention. The same notice names eight years for the invoice, the accounting vouchers and the generated eCH-0276 file — "the Fourth Bureaucracy Relief Act shortened that period from ten to eight years with effect from 1 January 2025" (§ 147 (3) AO, § 257 (4) HGB) — and for that reason "expressly does not promise complete erasure of your order data after processing"; for the duration of the period the data is blocked rather than erased (Art. 17 (3) (b) GDPR). A provider who promises both is contradicting itself. On the authority's side, LS 631.121 § 10 says only that the data is kept "in electronic form" — no duration is stated there.

6 · Format and version — why "we produce eCH-0276" is not yet a statement

On 5 August 2026 we measured the three schema files available to us; method: reading the attributes of the xs:schema element and set-comparing all xs:element names together with their declared types.

Between the first two columns — same namespace, same version attribute — 13 element names fall away, 15 are added, and for roughly 85 elements present in both the declared data type changes; the large majority move from the integer xs:long to the decimal xs:decimal. Two files with an identical namespace and an identical version attribute are therefore not the same file. The answerable question is consequently: against which file, from which source, with which checksum, retrieved when? That the standard is in motion is something the participants say themselves — the minutes of the cantonal tax office of Solothurn of 25 November 2025 record: "The standard 'eCH-0276' was brought into force as at 1 January 2025. Adjustments and corrections to the standard are currently still in progress."

One last detail separates the question of format from the question of route. The help article «Importieren und Exportieren» in the ZHcorporateTax support centre (created 28 July 2025, edited 16 September 2025) says of the import: "Select the desired zip file from the explorer in the input mask. By default the files are created with 'com.riag.jp.zh20xx'." Across all 70 articles of that help centre, "eCH-0276" appears zero times and "XBRL" zero times (our own count, retrieved 4 August 2026). We have never imported a file into a cantonal portal ourselves, and we therefore promise neither that an import will succeed nor that a portal will accept a file.

7 · The checklist — with our own answers beside it

One warning sign to close on. The canton keeps a register of professional tax representatives, the Treuhänder-Register. It "is not public", and entry in it "may not be made known to third parties in advertisements, on websites, on letterhead or in any other promotional form" (LS 631.121 § 12 para. 4). Anyone advertising with it is breaking the very rule they are invoking — and the entry would be no seal of quality in any case: «Weitere Abklärungen werden nicht vorgenommen», no further enquiries are carried out (§ 12 para. 2).

In short

• No homologation. The canton does not check private providers' products (ZStB 109c.3, 15 November 2005), and no connection for third-party software exists yet (Canton Zürich, 8 September 2025).
• The canton's own commitments are your template: no inspection before filing, encrypted transmission and storage, unalterable afterwards (LS 631.121 § 3) — a visible change log is not among them.
• "GDPR-compliant" answers the question about your figures only halfway: both statutes protect natural persons only; for balance-sheet figures it is the contract that counts.
• Credentials are not a detail: handing them over is the grant of authority (§ 11 para. 1), revocable with a new Zugangscode sent by post (para. 2).
• A format without a route is not an answer: eCH-0276 expressly does not govern transport or encryption (section 1.3), and three schema files all carry the same version attribute "0".
• The fastest test question there is: tell me your deletion period — and what runs on the day it expires.

Sources

• Verordnung über die elektronische Einreichung der Steuererklärung, LS 631.121 (Canton Zürich), of 18 October 2011, §§ 2, 3, 7, 9, 10, 11, 12 — version per the decree of 13 May 2025, in force since 1 July 2025 (Nachtrag 129).
• Merkblatt of the cantonal tax office on preparing the tax return with electronic aids (PC), ZStB 109c.3, issued 15 November 2005, in force from 1 January 2006.
• Canton Zürich, Finanzdirektion, Steueramt: «Fragen und Antworten, Online-Infoveranstaltung vom 25.08.2025», dated 8 September 2025.
• Canton Zürich, Steueramt: slides of the ZHcorporateTax information event, 25 August 2025.
• ZHcorporateTax support: «Importieren und Exportieren» (created 28 July 2025, edited 16 September 2025), «Steuererklärung löschen» (created 18 July 2025, edited 17 September 2025), and the article on the preview; count across all 70 published articles, retrieved 4 August 2026.
• eCH-0276 «E-Bilanz und E-Tax JP», version 1.0.0, status Genehmigt (approved), issued 19 November 2024 (decision of 2 December 2024), sections 1.3, 3, 4 — and draft version 2.0.0, issued 3 July 2026, «Ersetzt Version 1.0.0 – Major Change».
• Schema files eCH-0276-1-0.xsd, eCH-0276-1-0-4_20260115.xsd and eCH-0276-2-0-0.xsd; our own measurement of 5 August 2026.
• swissdec: «Technische Spezifikation eBILANZ — Anforderungen Transmitter», version 20260306, edition of 6 March 2026, chapters 2, 6, 7, 8.15 and Annex C.
• Digitale Verwaltung Schweiz: «Umsetzungsplan DVS 2026», 27 October 2025, project INM2.084 (delivery responsibility: Schweizerische Steuerkonferenz SSK).
• Cantonal tax office of Solothurn: minutes «Erfahrungsaustausch KSTA / EXPERTsuisse und TREUHAND|SUISSE», 25 November 2025, section 8.
• Canton Obwalden: help page for the declaration solution for legal entities (retrieved 4 August 2026), Merkblatt on the login (as at 18 February 2026), published guide to the E-Bilanz (as at 16 February 2023).
• agov.ch, information page on the AGOV authorities' login, retrieved 4 August 2026.
• Dr. Tax helpdesk: «Online-Einreichung / Fristen einreichen», article 115000806069, created 24 January 2017, last updated 3 July 2026.
• eBilanz Fabrik: Terms & Disclaimer (Switzerland), version of 4 August 2026; privacy notice for the Swiss offering, as at 4 August 2026.

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